NTLDR is missing
or
Boot: Couldn't find NTLDR
So
Boot using Windows Setup CD and go to "Recovery Console" by pressing "R". Then DOS mode will appear, Type your Administrator Password and Follow these Steps:
(type these commands)
copy G:\i386\ntldr c:\
copy G:\i386\ntdetect.com c:\
"G" is your CD drive, change it according to your system.
Enjoy !!!